


/// A trait which provides connection-specific functionality.
pub trait ManageConnection: Send + Sync + 'static {
    /// The connection type this manager deals with.
    type Connection: Send + 'static;

    /// The error type returned by `Connection`s.
    type Error: std::error::Error + 'static;

    /// Attempts to create a new connection.
    fn connect(&self) -> Result<Self::Connection, Self::Error>;

    /// Determines if the connection is still connected to the database.
    ///
    /// A standard implementation would check if a simple query like `SELECT 1`
    /// succeeds.
    fn is_valid(&self, conn: &mut Self::Connection) -> Result<(), Self::Error>;

    /// *Quickly* determines if the connection is no longer usable.
    ///
    /// This will be called synchronously every time a connection is returned
    /// to the pool, so it should *not* block. If it returns `true`, the
    /// connection will be discarded.
    ///
    /// For example, an implementation might check if the underlying TCP socket
    /// has disconnected. Implementations that do not support this kind of
    /// fast health check may simply return `false`.
    fn has_broken(&self, conn: &mut Self::Connection) -> bool;
}
